The Clear Air Act Amendment (CAAA) of 1990 requires industrial and commercial facilities to control emissions of a wide range of Volatile Organic Hazardous Air Pollutants (VOHAP), Volatile Organic Compounds (VOCs), particulates, and gases causing acid rain and precursors for depletion of stratospheric ozone layers. The CAAA contains 10 titles, each addressing specific guidelines and compliance rules for each area of concern.
Title III of the CAAA requires all industrial and commercial facilities located within "non-attainment" areas to reduce their VOC emissions below the threshold value. The term "non-attainment" means areas or metropolis which have not met the National Ambient Air Quality Standards (NAAQS) in terms of ozone, NO.sub.x and particulate matter.
Title III of the CAAA requires 174 source categories/industry groups requiring control of emissions of 188 Hazardous Air Pollutants (HAPs). Each source category is a specific type of industrial or commercial operations which emits pollutants to the ambient air. A facility becomes a major source when it emits over 10 tons per year of a single HAP, or over 25 tons per year of all HAPs combined into the air.
Further, industry and regions in all parts of the country are undertaking aggressive efforts to limit the release of all types of hazardous materials. Public reporting criteria have increased the scrutiny and public pressure on all industries which generate or release toxic or hazardous materials. As a result, many industries are undertaking renewed efforts to control the production or release of hazardous materials.
Title III of the CAAA exposes numerous industrial emission sources which were not regulated or controlled before. These sources require installation of emission control technologies. At present, many industrial and commercial facilities have turned to aqueous scrubbing techniques or thermal oxidation processes such as incineration to curb their emissions. Incineration, while achieving a high destruction efficiency, is expensive in terms of capital and operating costs. Further, off-site incinerators which may serve many industries, face ever more opposition from citizens who have health concerns over incinerations efficacy and safety. Incineration of halogenated VOCs and HAPs are also extremely corrosive to the contact parts and may produce highly toxic substances such as dioxin.
Aqueous scrubbing technologies for VOC control do not have the corrosion or toxic byproduct formation problems like the incineration technologies. However, the scrubbers can only be effective for hydrophilic VOCs and HAPs and also require effective means for disposal of scrub water. For hydrophobic contaminants, such as the majority of the regulated VOCs and HAPs, aqueous scrubbing is generally not effective for emission control.
Both the incinerator and the scrubber technologies are not well suited or compatible for accepting and treating facility wastewater. In other words, both the technologies are applicable for treatment of only air streams. For hydrophilic contaminants, scrubbers could potentially use facility wastewater. However, since scrubbers merely transfer the contaminants from the gaseous to the liquid phase, and do not destroy, degrade or decompose, other forms of treatment operation(s) are necessary to dispose or discharge the scrub water.